In curing ultraviolet-sensitive layers and in other applications employing ultraviolet light, it is desirable to have a means of generating a high-intensity ultraviolet image or an unresolved ultraviolet flooding beam. Visible-light lamps are a conventional source of ultraviolet radiation, but only a very small percentage of the total radiation they emit is ultraviolet, resulting in tremendous energy waste, much of it in the form of bothersome heat.
Prior art night-vision devices, such as those employed by the military, provide amplification of visible light by converting incoming visible light to electrons, accelerating the electrons across a strong electric field through hollow fibers the inside surfaces of which emit additional electrons, and converting the amplified electron radiation to visible light at a phosphor screen.
An article in Inside R&D, Vol. 7, No. 6, published Feb. 8, 1978, discloses a thin panel CRT tube of Texas Instruments that includes a matrix of area cathode electron emitters spaced in back of a screen coated with visible-light luminescing phosphors, all inside an evacuated chamber.
Houston et al. U.S. Pat. No. 4,069,438 shows a device for producing an electrostatic image of an X-ray beam on a Mylar sheet. The X-ray beam strikes an ultraviolet fluorescent layer such as BaSO.sub.4 :Pb, the ultraviolet light thus produced passes through a quartz layer to a layer of ultraviolet-sensitive electron-emitting material, the emitted electrons pass through a gas filled region under the influence of an electric field to ionize the gas, and a Mylar insulating layer is positioned at the anode so as to be struck by the ions produced.